What is Conficker?
Conficker, also known as Downadup or Kido, is the latest super virus to spread around the Internet and has security experts in a panic.

The worm isn’t just exploiting a networking hole, however; it features a sophisticated method of cracking administrator passwords, making it difficult to remove, and also copies itself to USB drives so that it can spread even when the online flaw is plugged.Source

This nasty worm is supposed to be active on april 1st. Here are some steps that you can take in dealing with this worm:

Your first step should be the tools you already have: Windows Update, to make sure your computer is fully patched, and your current antivirus software, to make sure anything that slips through the cracks is caught.

But if Conficker’s already on your machine, it may bypass certain subsystems and updating Windows and your antivirus at this point may not work. If you are worried about anything being amiss — try booting into Safe Mode, which Conficker prevents, to check — you should run a specialized tool to get rid of Conficker.

Microsoft offers a web-based scanner (note that some users have reported it crashed their machines; I had no trouble with it), so you might try one of these downloadable options instead: Symantec’s Conficker (aka Downadup) tool, Trend Micro’s Cleanup Engine, or Malwarebytes. Conficker may prevent your machine from accessing any of these websites, so you may have to download these tools from a known non-infected computer if you need them. Follow the instructions given on each site to run them successfully. (Also note: None of these tools should harm your computer if you don’t have Conficker.)

As a final safety note, all users — whether they’re worried about an infection or know for sure they’re clean — are also wise to make a full data backup today.

What won’t work? Turning your PC off tonight and back on on April 2 will not protect you from the worm (sorry to the dozens of people who wrote me asking if this would do the trick). Temporarily disconnecting your computer from the web won’t help if the malware is already on your machine — it will simply activate once you connect again. Changing the date on your PC will likely have no helpful effect, either. And yes, Macs are immune this time out. Follow the above instructions to detect and remove the worm.